Answered by Shaykh Faraz Rabbani
Question: Can I Combine My Intention for a Missed Ramadan Fast and An Optional Sunnah Fast (Such as Shawwal, Muharram, Mondays, etc.)?
Walaikum assalam wa rahmatullah,
Yes, it is valid to make the intention to make up missed Ramadan fasts and to make a secondary ’sunna’ intention–such as fasting the six days of Shawwal, or the sunna of fasting Mondays and Thursdays.
And Allah alone gives success.
This answer was collected from Seekersguidance.org. It’s an online learning platform overseen by Sheikh Faraz Rabbani. All courses are free. They also have in-person classes in Canada.